POWER9 is IBM's most recent POWER compatible server and workstation CPU ([[PowerISA|POWER ISA]] v3.0B). Built on a 14nm process, each CPU package can contain up to 24 [[SMT4|SMT4]] cores or 12 [[SMT8|SMT8]] cores. Each pair of [[SMT4|SMT4]] cores, or singleton [[SMT8|SMT8]] core, comprises a slice; each slice in turn contains 512kB L2 cache and 10MB L3 cache. Raptor Computing Systems' 4- and 8-core processors provide unpaired cores, such that one [[SMT4|SMT4]] core per slice is fused off. This allows each of the [[SMT4|SMT4]] cores to utilize the full cache of the slice exclusively, increasing performance for these [[Single_Thread|ST]]-focused processors.

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POWER9 is IBM's most recent POWER compatible server and workstation CPU ([[Power ISA|POWER ISA]] v3.0B). Built on a 14nm process, each CPU package can contain up to 24 [[SMT4|SMT4]] cores or 12 [[SMT8|SMT8]] cores. Each pair of [[SMT4|SMT4]] cores, or singleton [[SMT8|SMT8]] core, comprises a slice; each slice in turn contains 512kB L2 cache and 10MB L3 cache. Raptor Computing Systems' 4- and 8-core processors provide unpaired cores, such that one [[SMT4|SMT4]] core per slice is fused off. This allows each of the [[SMT4|SMT4]] cores to utilize the full cache of the slice exclusively, increasing performance for these [[Single_Thread|ST]]-focused processors.

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==Process==

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POWER9 is fabricated using the GlobalFoundries 14HP (High Performance) process. This is distinct from the GlobalFoundries 14LPP (Low Power) process used by other GF 14nm customers, and is believed to be an IBM-specific process using ex-IBM Microelectronics intellectual property. The process is also used for the CPUs in IBM's z14 mainframes. [https://fuse.wikichip.org/news/956/globalfoundries-14hp-process-a-marriage-of-two-technologies/ A detailed discussion of 14HP and how it differs from 14LPP is available here.]

Nimbus is the &#8220;[[Scale Out|scale out]]&#8221; variant and uses direct-attach DDR4 memory. Cumulus is the &#8220;[[Scale Up|scale up]]&#8221; version and uses [[Centaur]] memory buffers, allowing larger amounts of memory to be attached to a system.

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Chips can be fused as [[SMT4]] or [[SMT8]] during manufacturing. The [[SMT8]] variant essentially fuses each pair of cores into one &#8220;core&#8221;, halving the core count while doubling the number of threads per core. [[SMT4]] variants are intended for [[PowerNV]] platforms running Linux, and [[SMT8]] variants are intended for use with IBM's PowerVM hypervisor which can run Linux, AIX or IBM i.<ref>Stuecheli, Jeff. POWER9. Presentation for [https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/Power+Systems/page/AIX+Virtual+User+Group+-+USA AIX VUG]. ([https://public.dhe.ibm.com/systems/power/community/aix/Central-VUG-Replays/2017-01-26_IBM_POWER9.wmv video download], [https://www.ibm.com/developerworks/community/wikis/form/anonymous/api/wiki/61ad9cf2-c6a3-4d2c-b779-61ff0266d32a/page/1cb956e8-4160-4bea-a956-e51490c2b920/attachment/56cea2a9-a574-4fbb-8b2c-675432367250/media/POWER9-VUG.pdf slides], [[User:Torpcoms/Timemark/POWER9|timemarks]])</ref>

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== Modules ==

{| class="wikitable"

{| class="wikitable"

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|

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|+ POWER9 Modules

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!PowerNV

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! Chip

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!PowerVM

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! Module

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! Memory Channels

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! XBUS Lanes

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! PCIe Lanes

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! OpenCAPI Lanes

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! Socket

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|-

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!Scale Out

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!rowspan="3"|Nimbus

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|Nimbus (Sforza, Monza, LaGrange)

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| [[Sforza]]

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|?

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| 4

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| 1

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| 48

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| 0

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| LGA 2601

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|-

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!Scale Up

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| [[Monza]]

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| 8

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|Cumulus (?)

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| 1

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| 34

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| 48

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| LGA 3899

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|-

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| [[LaGrange]]

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| 8

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| 2

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| 42

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| 16

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| LGA 3899

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|-

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! Cumulus

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| (unknown)

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| (memory attached via [[Centaur|Centaurs]])

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| (unknown)

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| (unknown)

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| (unknown)

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| ?

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|-

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! Axon

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| (unknown)

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| (memory attached via OMI)

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| Up to 3

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| Up to 48

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| Up to 48

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| ?

|}

|}

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'''''XBUS''' is used for inter-processor communication on dual-socket system''

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=== Nimbus ===

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Nimbus chips are available in three different modules: [[Sforza]], [[Monza]], and [[LaGrange]]. Each module uses the same silicon mask but is packaged differently, exposing different I/O functionality to the host platform, allowing purpose-built systems to be constructed in addition to more general-purpose computers.

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'''[[Sforza|Sforza]]''' is the most flexible of these packages, providing PCIe 4.0 lanes as the main I/O resource, and is what [[Talos_II|Talos™ II]] uses for maximal similarity to existing desktop, workstation, and server systems.

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'''[[Monza|Monza]]''' modules offer the most OpenCAPI/NVLink bandwidth and are used in IBM's AC922 (Witherspoon) systems, such as those used by the Sierra and Summit supercomputers.

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'''[[LaGrange|LaGrange]]''' modules offer increased XBus bandwidth between processor sockets and are used by the Google/Rackspace Zaius motherboard used in the Barreleye G2 system.<ref>Gangidi, Adi [https://blog.rackspace.com/zaius-barreleye-g2-server-development-update-2 Zaius/Barreleye G2 Server Development Update]. 2017-11-13</ref>

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Part numbers for different POWER9 Sforza SKUs can be found on page 58 of the [[:File:POWER9 Sforza DS v16 23JUL2018 pub.pdf|datasheet]]. These part numbers are printed on the surface of the CPU module and can be used to determine the type of the CPU.

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Several revisions of the Nimbus mask have been issued:

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* DD2.1 was the final preproduction revision before GA. It has errata preventing the use of hardware virtualization, but DD2.1 Sforza can be used in e.g. the [[Talos II]] if this functionality is not needed.

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* DD2.2 is the first GA revision of Nimbus. DD2.2 Sforza is sold at [https://raptorcs.com/ raptorcs.com].

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* DD2.3 is an updated revision of Nimbus, pending announcement.

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=== Cumulus ===

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Little is known about Cumulus chips at this time; as Scale Up chips, they will trade some I/O bandwidth for support for more than two sockets.<ref>Morgan, Timothy Prickett. [https://www.nextplatform.com/2017/12/05/power9-to-the-people/ POWER9 to the People]. 2017-12-05</ref>

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=== Axone ===

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Branded POWER9&prime; ("POWER9 Prime"), also known as POWER9 with Advanced I/O. Newly announced in August 2019. Uses serial memory attachment via OMI, an evolution from the [[Centaur]].

[[PowerNV|PowerNV]] systems use [[SMT4|SMT4]] packages exclusively, and are available in three different sockets of the Nimbus chip: [[Sforza|Sforza]], [[Monza|Monza]], and [[LaGrange|LaGrange]]. Each socket type exposes different I/O functionality to the host platform, allowing purpose-built systems to be constructed in addition to more general-purpose computers. [[Sforza|Sforza]] is the most flexible of these packages, providing PCIe 4.0 lanes as the main I/O resource, and is what [[Talos_II|Talos™ II]] uses for maximal similarity to existing desktop, workstation, and server systems.

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== External Links ==

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PowerVM systems, in contrast, use SMT8 chips, and are intended to run Linux, AIX, or IBM i under IBM's PowerVM hypervisor. SMT8 chips are planned to be made in both [[Scale Out|Scale Out]] (direct-attach RAM) and [[Scale Up|Scale Up]] (centaur-buffered RAM) configurations.

POWER9 is IBM's most recent POWER compatible server and workstation CPU (POWER ISA v3.0B). Built on a 14nm process, each CPU package can contain up to 24 SMT4 cores or 12 SMT8 cores. Each pair of SMT4 cores, or singleton SMT8 core, comprises a slice; each slice in turn contains 512kB L2 cache and 10MB L3 cache. Raptor Computing Systems' 4- and 8-core processors provide unpaired cores, such that one SMT4 core per slice is fused off. This allows each of the SMT4 cores to utilize the full cache of the slice exclusively, increasing performance for these ST-focused processors.

Contents

Process

POWER9 is fabricated using the GlobalFoundries 14HP (High Performance) process. This is distinct from the GlobalFoundries 14LPP (Low Power) process used by other GF 14nm customers, and is believed to be an IBM-specific process using ex-IBM Microelectronics intellectual property. The process is also used for the CPUs in IBM's z14 mainframes. A detailed discussion of 14HP and how it differs from 14LPP is available here.

Chips

Nimbus is the “scale out” variant and uses direct-attach DDR4 memory. Cumulus is the “scale up” version and uses Centaur memory buffers, allowing larger amounts of memory to be attached to a system.

Chips can be fused as SMT4 or SMT8 during manufacturing. The SMT8 variant essentially fuses each pair of cores into one “core”, halving the core count while doubling the number of threads per core. SMT4 variants are intended for PowerNV platforms running Linux, and SMT8 variants are intended for use with IBM's PowerVM hypervisor which can run Linux, AIX or IBM i.[1]

Nimbus

Nimbus chips are available in three different modules: Sforza, Monza, and LaGrange. Each module uses the same silicon mask but is packaged differently, exposing different I/O functionality to the host platform, allowing purpose-built systems to be constructed in addition to more general-purpose computers.

Sforza is the most flexible of these packages, providing PCIe 4.0 lanes as the main I/O resource, and is what Talos™ II uses for maximal similarity to existing desktop, workstation, and server systems.

Monza modules offer the most OpenCAPI/NVLink bandwidth and are used in IBM's AC922 (Witherspoon) systems, such as those used by the Sierra and Summit supercomputers.

LaGrange modules offer increased XBus bandwidth between processor sockets and are used by the Google/Rackspace Zaius motherboard used in the Barreleye G2 system.[2]

Part numbers for different POWER9 Sforza SKUs can be found on page 58 of the datasheet. These part numbers are printed on the surface of the CPU module and can be used to determine the type of the CPU.

Several revisions of the Nimbus mask have been issued:

DD2.1 was the final preproduction revision before GA. It has errata preventing the use of hardware virtualization, but DD2.1 Sforza can be used in e.g. the Talos II if this functionality is not needed.

DD2.2 is the first GA revision of Nimbus. DD2.2 Sforza is sold at raptorcs.com.

DD2.3 is an updated revision of Nimbus, pending announcement.

Cumulus

Little is known about Cumulus chips at this time; as Scale Up chips, they will trade some I/O bandwidth for support for more than two sockets.[3]

Axone

Branded POWER9′ ("POWER9 Prime"), also known as POWER9 with Advanced I/O. Newly announced in August 2019. Uses serial memory attachment via OMI, an evolution from the Centaur.